The percussion mechanism of a traditional piano is a set of levers designed to control the strokes from the mallet to the string, thereby allowing a pianist to modulate the instrument's expression of sound. Said mechanism comprises four main parts; namely, the mallet or hammer, the key, the wippen and the damper.
The basic operation of traditional pianos begins with the pianist pressing the key; this activates a lever that moves a hammer which, in turn, strikes the corresponding key whilst simultaneously raising the damper, such that the string vibrates until the key is released; at this time, the damper falls onto the string, causing it to stop vibrating and producing sound.
Traditional pianos may be divided into two major categories: grand pianos, which have large dimensions, and wherein the strings and the resonance box are in a horizontal position, and upright pianos, which are characterised in that the strings, the mallets and the resonance box are in a vertical position, perpendicular to the floor. Due to their smaller dimensions, the latter are the most habitual in household environments.
In regards to the piano pedals, their function is to modify or alter the sound produced and, to this end, they are operated with the tips of the toes without raising the heel from the floor. In all types of pianos, there are three different pedals: the left, the middle and the right pedal.
The function of the left pedal, also occasionally called una corda pedal, is to bring the percussion hammers closer to the string, in order to attenuate the intensity of the sound obtained when striking upright pianos. In general, it is only used for some specific passages that require minimum intensity. The middle pedal, which in upright pianos has a muffler function, interposes a felt curtain between the hammers and the strings, which considerably reduces the intensity of the sound obtained.
Finally, the right pedal or sustain pedal causes the dampers of all the strings to rise, thereby producing a longer duration of the sound obtained from striking the string, as well as greater richness of sonority upon activating the harmonics; on the contrary, when the pedal is no longer operated with the foot, the dampers once again fall onto the strings, thereby extinguishing the sound. It is the most commonly used pedal in piano playing.
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